字符常量'a'‘z'‘A'‘Z'"o'"g'"n'ASCII字符集：列出所有可用的字符每个字符：惟一的次序值（ASCI码）ASCII码表符号符号10 进制符号10 进制符号10进制10进制'0'-'9'P80112@6496PQ81q1136597A'A'-Z'R82114HB6698bs83115067C99'a'-'z'T84x116D68d100D851174E69101e486118470f102FW87w119G71103g区分数字1和X88120x72Hh104Y89121y13Ii105数字字符"1'290122N74J106J[91123375Kk10719212476L1108193112577M109I94126Nto110n095127111079'a' 'z' 'A' 'Z' '0' '9' ' ' '\n' 字符常量 ASCII字符集：列出所有可用的字符 每个字符：惟一的次序值（ ASCII 码） '0'-'9' 'A'-'Z' 'a'-'z' 区分数字 1 和 数字字符 '1